feat(filelink): add set soruce method

[pcholuj]

Add setSource method to filelink class

[codecov]

Codecov Report

Merging #270 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #270      +/-   ##
=========================================
+ Coverage    99.1%   99.1%   +<.01%     
=========================================
  Files          32      32              
  Lines        1454    1456       +2     
  Branches      210     210              
=========================================
+ Hits         1441    1443       +2     
  Misses         13      13

Impacted Files	Coverage Δ
src/lib/filelink.ts	100% <100%> (ø)	⬆️

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